1. Field of the Invention
Embodiments of the present invention are related to eddy current inspection devices, and more particularly, to inspection devices that include arrays of magnetoresistive sensors for measuring the curl of magnetic field signals effected by eddy currents encountering flaws.
2. Description of Related Art
Non-destructive evaluation (NDE) of a component to detect flaws or other features within the component may be performed by various techniques that include X-ray radiography, ultrasonics, acoustic emissions, and eddy currents. In particular, eddy current inspection devices are commonly used for NDE of electrically conductive components. Eddy current inspection devices typically use one or more excitation coils to generate an alternating magnetic field, which in turn induces eddy currents in the component.
The eddy currents induced in the component under inspection effect a magnetic field. However, when an eddy current encounters an internal flaw of the component, the eddy current flows around the flaw and changes the magnetic field. The pickup coil of the inspection device detects the resultant signals inductively. This detection provides information regarding the location and size of the flaw within the component.
These inductively detected signals are a time derivative of the actual magnetic field signals that are indicative of flaws. To improve the understandability or comprehendability of the measurements taken by the inspection device, a need exists to measure the current density giving rise to the magnetic field rather than the time derivative. Such measurements of current density would enable detection of flaws with improved visualization for the operator. Therefore, a need exists for an eddy current inspection device that accurately determines the current density resulting from the magnetic field signals effected by flaws.